Cutting oil base



Patented Jan. 29, :1946

CUTTING 01L BASE Latimer D. Myers, Cincinnati, and Victor J; Muckerheide, Silver-ton, Ohio, assignors to Emery Industries, Inc., Cincinnati, Ohio, a corporation of Ohio No Drawing. Application May 20, 1942, Serial No. 443,842

7 Claims. ('01. 252-32) This invention relates to cutting oils, that is,

compositions consisting essentially of mineral oil but characterized by their ability to emulsify with water. The emulsions produced from such cutting oils are used in the machining of metals for the purpose of cooling the metal cutting tool and providing lubrication for the chips at the cutting edge. Thus, a cutting oil consists, generally speaking, of a mineral oil containingan emulsifying compound capable of producing an emulsion of the oil in water.

I This invention is addressed, more particularly, to cutting oil bases, that is, compounds adapted to be added to ordinary mineral oils to endow them with emulsifying characteristics.

When cutting oils first came to be used in the metal trades many years ago they contained a great variety of different materials, the composition of the product of each manufacturer being in the nature of a proprietary made up to suit a given machine shops requirements. Because of the relatively delicate. proportioning required to produce emulsions with the compounds then available each batch of cutting oil was adjusted chemically upon the basis of its ability to emulsify the particular grade or type of mineral oil from which the cutting oil was to be produced. There was always substantial variation from batch to batch, and even so, the actual emulsifiability of the oil in water'was poor as judged by the specifi cations of the present day. Most of the original compositions were mineral oils containing a limited quantity of fatty acid soap, sometimes naphthenic acids and sometimes free fatty acids for the purpose 'of enabling the soaps to dissolve in composition would have to be made and emulsifying assistants would have to be added to the compositions in order that their emulsifying characteristicswould conform to prescribed standards. The problem was not merely one of adding more of the emulsifying base; if a suitable emulsion flnery.

With the more widespread use of cutting oil in.

could not be obtained by using 10% of base sulphonate, it was the experience, always unexpected and disappointing, that a suitable emulsion could still not be obtained by using 12, 15,

or 20%. In order. to obtain a satisfactory emulsion under such circumstances some extraneous material such as diethyleneglycol would haveto be added. Obviously, the procedure of making chemical adjustments each time a batch of cutting oil base was to be made was both tedious and expehsive. Moreover, a base suitable for emulsifying the oil, produced at one refinerywould not be capable of producing a suitable cutting oil upon admixture with the oil from a different reall machine trades, this necessity of making 4 chemicaladjustments has become a problem of serious importance and, to avoid it,the objective of the present invention has been to produce cutting oil bases which are at least as inexthe mineral oil. The acidity frequently caused corrosion of the metals. v In more recent years oil soluble mineral oil sulphonates have been introduced into mineral oil v to endow it with emulsifying properties.

The use of mineral oil-sulphonates was a substantial advance inasmuch as the cutting oils so produced were neutral or substantialy so and the sulphonates were better emulsifying agents than those previously available. Many thousands of pounds of gutting oil base, consisting chiefly of mineral oil ulphonates, have been used-in" recent years in cutt g oil production, the base being added to the oil the refinery and the resulting cutting oil then being shipped to the consumer.

The chief difliculty with. the use of mineral oil sulphonate cutting oil bases has been their intolerance to variations in the type or quality of oil they were to emulsify. Each time a batch of cutting oil was made up adjustments in chemical pensive as the sulphonate bases which we have had available in the past, but better than sulphonate bases, because of their tolerance to variations in oil, their tolerance to variation in water conditions and because of the strong" and powerful emulsifying action they'are capable of exerting on a variety of types and grades of oil.

The objective, in other words, has been to produce a cutting oil base capable of emulsifying the diiferent'kinds of oil produced at the different refineries throughout thecountry, and of emulsifying such oil with the varying kinds of water found at manufacturers plants.

We have discovered that a cutting oil base consisting essentially of rosin soap of an alkali metal and a fatty acid mono ester of-a poly or dihydric alcohol is capable of giving these'desirable-results. A typical base of the present invention consists of substantially 1 part of fatty acid mono ester to each l to 2 parts of rosin soap. The proportions are quite critical, otherwise the desired universal emulsifying characteristics are not obtained.

It has been appreciated in the past .that the fatty acid monoesters are capableof carrying preferably fatty able as the principal constituents of cutting oils for several reasons. .If they are in theproportions in which rosinsoap to fatty acid mono ester is present in the compositions of this invention the red oil soap is incapable of dissolving in the oil.' And. while more of the fatty acid mono ester is capable of causing the red oil soap to dissolve in mineral oil, the oil then either gels and loses its fluid characteristics or does not emulsify in water. In the same manner, that a soap of a fatty acid does not give satisfactory results when combined 4 liar and very desirable response to fatty acid mono esters by the rosin soap. Such a material, when in the proper proportion to the mono ester, is capable of exerting the required emulsifying action upon a variety of mineral oils and of emulsifying such oils with a variety of difierent types of water, both acid and alkaline. The base itself is a substantially neutral composition and exerts no corrosive action on metals.

The products of the present invention therefore, which are capable of providing the desired emulsifying properties as well as the toleration to variations in both the oil and water with which theysubsequently are admixed, consist essentially of an alkali metal soap of rosin and a fatty acid mono ester of a polyhydric or dihydric alcohol.

The alkali metal of choice which is used for saponifying the rosin is potassium, the rosin soap thus being, chiefly, potassium abietate. Sodium may be employed as a substitute for potassium in saponifying the rosin, though the base is heavier. In this case it is usually desirable to dilute the base with mineral oil in order to make'is suiiiciently thin to be poured from shipping containers without diiiiculty.

The fatty acids adapted to be employed in the practice of the present invention are preferably liquid fatty acids obtained from natural fats and acid containing from 16 to 18 carbon atoms in chain length as, for example, oleic acid, comoil fatty acids, soybean fatty acids and the like. The solid fatty acids and particularly'the mono esters ,of them are less soluble in mineral oil than the mono esters of the liquid fatty acids and sometimes tend to crystallize out of the oil if the composition becomes chilled.

Ethylene glycol, diethylene glycol, glycerol and the like are typical alcohols which may be employed in the preparation of the present compositions. However, as between the poly and dihydric alcohols,- the polyhydric alcohols are preferred inasmuch as, in the present compositions, the polyhydric alcohol esters are much more effective than the dihydric alcohol esters in promoting emulsiflability and the solubility which is desired. For these reasons the esters of the dihydric alcohols may be considered as the partial equivalents, not the full equivalent of the polyhydric alcohol esters in the practice of this improvement. In general, wood rosin is preferred to gum rosin in the preparation of the rosin soap employed in the compositions.

In the manufacture of the present cutting oil base the mono ester and the rosin soap are preferably made independently of one another and then admixed in the proper ratio. The mono ester is made by heating hrcerine and fatty acid to a high temperature until the free fatty acid has been reduced to about 2%. T While the ester is warm ,Potassium hydroxide sufilcient in amount to rosin is added in the desired proportion and the ester and the rosin are then admixed. The rosin i more easily saponifled and handled when dissolved in the ester than when saponifled directly.

saponify the rosin is then added and, after saponification is complete, the cutting oil base i ready for use.

A typical cutting oil base of the present invention is of the following proximate-analysis:

If desirable ,oil soluble mineral oil sulphonates may be used as emulsifying adjuncts in the present compositions up to approximately 10 or 15% by weight. A feature of considerable importance in this respect is that the presence of sulphonates in the present cutting oil bases does not disturb or destroy their toleration for variations in the quality of oil which they are capable of emulsifying. This fact enables the manufacturer to include sulphonates in the composition when the price of rosin is high and, conversely, to exclude sulphonates when they are in demand, thereby keeping the cost of the product at a minimum under fluctuating market conditions. Mineral oil sulphonates up to approximately 40% by weight may be employed when desirable.

In the manufacture of cutting-oils from these bases the proportion utilized ordinarily resides in the range of 12 to 20 parts of base to each 100 parts of mineral oil.

In contrast with the mahogany sulphonate type cutting oil bases that have been available in the past, the quality of an emulsion obtained by the bases of the present invention is influenced by the amount of base employed. If a poor emulsion is obtained using a given amount of base, a good emulsion can readily be made, except under unusual conditions, by using a larger quantity. This property enables each cutting oil manufacturer to use a minimum quantity of base to produce the necessary emulsion with the particular mineral oil from which the given cutting oil is being made.

Having described our invention we desire to be limited as to the scope thereof only by the claims which follow:

- substantially 1 to 2 parts by-weight of rosin soap to each 1 part of glyceryl mono oleate.

4. A cutting oil base consisting essentially of a mono ester of a fatty acid from 16 to 18 carbon atoms in chain length and a dihydric alcohol in admixture with a rosin soap of an alkali metal, the proportion of said ingredients being substantially one part of fatty ester to 1-2 parts of rosin soap.

5. A cutting oil base consisting essentially of a mono ester of a fatty acid from 16 to 18 carbon atoms in chain length and a polyhydric alcohol in admixture with a rosin soa of an alkali metal, the proportion of said ingredients being substantially one part of tatty to 1-2 of resin 0 so. o

6. A cutting oil base consisting essentially of substantially 1 to 2 parts rosin soap oi analkali metal, one part glyoerylmono oleate, the said cutting 011 base being oharacterized'in its ability to .produoe, strong and lasting emulsions of mineral oil in water substantially independent of 'variations in the quailtyot the mineral oil and chemical consistency of the water.

'1. a cutting oil base consisting essentially or a mono ester of a liquid fatty acid of from 16 to 18 carbon atoms in chain length and apolyhydric alcohol in admixture ,with potash rosin soap in the nroportions ot substantially 1 to 2 parts by weight or rosin soap toeach part or fatty acid VICTOR J. 

